Olefin polymerization catalysts are of great use in industry. Hence there is interest in finding new catalyst systems that increase the commercial usefulness of the catalyst and allow the production of polymers having improved properties.
Catalysts for olefin polymerization are often based on metallocenes as catalyst precursors, which are activated either with an alumoxane or with an activator containing a non-coordinating anion.
U.S. Pat. No. 7,829,495 discloses alkyl substituted metallocenes having a “ . . . C3 or greater hydrocarbyl . . . substitutent bonded to either the LA or LB ring through a primary carbon atom . . . preferably an n-alkyl substituent . . . ” (see column 4, lines 9-12). Further, in the Examples section, (n-propylcyclopentadienyl)(tetramethylcyclopentadienyl)zirconium dichloride combined with methylalumoxane and Davision™ 948 silica is used for ethylene hexene polymerization; bis(n-propyl cyclopentadienyl) zirconium dichloride combined with methylalumoxane and Davision™ 948 silica is used for ethylene hexene polymerization; and dimethylsilyl(flourenyl)(n-propyl cyclopentadienyl) zirconium dichloride combined with methylalumoxane and Davision silica is used for ethylene hexene polymerization.
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There is still a need in the art for new and improved catalyst systems for the polymerization of olefins, in order to achieve specific polymer properties, such as high melting point, high molecular weights, to increase conversion or comonomer incorporation, or to alter comonomer distribution without deteriorating the resulting polymer's properties.
It is therefore an object of the present invention to novel catalyst compounds, catalysts systems comprising such compounds, and processes for the polymerization of olefins using such compounds and systems.